Fleece Performance Engineering Internal Wire Harness Connector Seal — 20‑Pin Black, Direct‑Fit for Allison LCT1000/2000 & GM 4T65‑

Fleece Performance Engineering’s 20‑pin internal wire harness connector seal replaces worn OE seals to stop oil ingress into Allison LCT1000/2000 and GM 4T65‑E transmission harnesses.

If your transmission harness connector leaks oil or the original internal seal is brittle or missing, this drop‑in replacement from Fleece Performance Engineering restores the internal seal path and includes a new connector body and O‑ring so you don’t have to hunt for scarce OE parts. The kit matches the fit and function of the original 20‑pin internal seal used in many Allison LCT series units and GM 4T65‑E transmissions, and it’s designed to work with specific OE internal harness part numbers for a precise repair.

What problem does this internal connector seal solve?

Over time the factory internal seal that keeps transmission fluid out of the harness cavity can harden, crack, or fall out while servicing the unit. This kit restores a fluid‑tight internal barrier so stray oil won’t travel into pins and wiring, which can cause corrosion or intermittent electrical faults. It replaces the hard‑to‑find original seal and supplies a new connector body and O‑ring for a full internal repair.

• Restores the sealed interface between harness and transmission
• Prevents oil migration into connector pins and wiring
• Includes replacement connector body and O‑ring for complete repair
• Direct fit for 20‑pin internal harness applications

Which transmissions and harness part numbers is this compatible with?

This Fleece Performance seal is built for Allison LCT1000 (2001–2019) and LCT2000 series transmissions as well as GM 4T65‑E applications that use the same 20‑pin internal seal design. It intentionally fits OE internal harnesses carrying the listed part numbers so you can match your harness before purchasing. Confirming the OE P/N on your harness ensures a correct fit and avoids misapplication.

• Compatible: Allison LCT1000 (2001–2019) and LCT2000
• Compatible: GM 4T65‑E transmissions
• Fits OE internals with P/Ns: 29545307, 29541371, 29539792, 29543336
• 20‑pin configuration for exact replacement

What comes in the kit and how does installation work?

The package contains the 20‑pin internal connector seal, a replacement connector body, and the O‑ring for the connector housing. Installation is a direct replacement of the existing internal seal and requires basic transmission connector disassembly—no specialized tools beyond common hand tools are typically required. Follow standard cleaning and reassembly steps to ensure the new O‑ring and seal seat correctly for a durable repair.

• Included: 20‑pin internal seal, connector body, and O‑ring
• Direct substitute for hard‑to‑find OE seals
• Requires cleaning the connector cavity and careful seating of the O‑ring
• Typical install uses basic hand tools and standard connector service steps

How long can I expect this replacement to last and what should I watch for?

This replacement is engineered to match OE fit and materials so, when installed correctly, it provides long‑term protection comparable to the original part. Inspect the connector for proper seating and the O‑ring for damage during routine service intervals; repeated exposure to contaminated fluid or improper seating can shorten lifespan. If you still see oil at the connector after installation, double‑check the mating face and O‑ring orientation before assuming a different failure source.

• Designed to OE fit standards for durable sealing
• Inspect O‑ring and seating during routine maintenance
• Recheck connector mating face if leaks persist after install
• Avoid contaminated fluids and rough handling to maximize life

Who is this for: Technicians, DIY enthusiasts, and fleet maintenance teams working on Allison LCT1000/LCT2000 or GM 4T65‑E transmissions who need a reliable, direct replacement for missing or failed 20‑pin internal harness seals. It’s especially useful when original OE seals are discontinued or difficult to source and you want a single kit that includes the connector body and O‑ring to complete the repair without multiple separate parts.